Air spring



Oct. 12 1926.

J. J. MGELROY AIR SPRING INVENTOR HIS A TOR' EEYS w 5 m g 410 5 0 6 W MAW 7 \\W\ J\\\\ (7/ Alf 3 2 Z B 9 3 mvflln M m 1... it? 7 a; w a \N\ Q 6 Z 2 M M zm zy fi 3 Patented Oct. 12, 1926.

UNITED STATES v PATENT'OFFICE.

JOHN J. MGELROY, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO THE WESTINGHOUSE AIR SPRING COMPANY, OF NEW HAVEN, CONNECTICUT, A CORPORATION OF PENN- SYLVANIA.

AIR SPRING. I

Original application filed March 27, 1923, Serial No. 628,087. Divided and this application filed April 15,

This invention relates to pneumatic cush ion devices and methods of operating the same, useful in the arts generally, and particularly in connection with vehicles and the like.

One object of the present invention is to provide a device comprising essentially a cylinder with .a closed top divided by a piston having a sliding fit therein; the space above the piston being the main cushion chamber containing air usually under pres sure and a suitable quantity of oil to serve as an oil seal for preventing air leakage; and the space below the piston containing atmospheric air admitted thereinto through the leaky mechanical seal or packing between the piston rod and the bottom wall of the cylinder, the chamber thus provided at the lower end of the cylinder serving to gradually check the recoil or rebound of the piston.

' Another object is the provision in such a structure of means'for collecting oil leaking pastthe seal and restoring it to the chamber 95 above the seal at appropriate periods in the operation of the device.

Another object is the provision of means in the collecting chamber for positively causing the return of the stored oil to the cushion chamber, said last named means being brought into operation at appropriate times by and during the operation of the spring members, whereby the life of th spring is prolonged indefinitely.

Another object is the provision of means in said device for confining the atmospheric air to the lower chamber, thus preventing or restraining thepassage thereof into the c01- lecting chamber or the cushion chamber.

Other objectsand features of novelty are pointed out hereinafter and in the appended claims.

In the accompanying drawing I have shown by way of illustration a sectional ele- 45 vation of one form of pneumatic spring embodying my new method of, and apparatus for operating such devices.

The device consists of a suitable length of tubing 3, to the upper end of which a dome 60 shaped head 4 is threaded, and to the lower end of which a cup-shaped casting 5 is threaded.

A piston or plunger carrying two annu-- lar cup-shaped packings 6 and 7 is arranged Serial No. 28,173.

to slide within tubing 3 and divides the in- B5 terior of the air spring into a variable volume load supporting cushion chamber 8 and a rebound or recoil check chamber 9.

A piston rod 10" carries the piston or plunger and projects through the bottom 11 of the air spring and is connected by nut 12 to the outer end of a leaf spring of a vehicle, while cup-shaped member 5 is-suitably connected to a front horn or a leaf spring attached to the vehicle frame, as 1s now well understood in the art.

The piston of the air spring preferably consists of a lower annular nut or base 13 threaded onto the piston rod 10 and an upper annular nut or follower 14 threaded onto I the upper end of the piston rod 10 or held in place against a shoulder 15 thereon by a threaded nut 16. These two nuts 13 and 14 form supports for the cup packings 6 and 7 and their outer peripheries are preferably finished so as to form bearing surfaces adapted to slide on' the inner surfaces of cylinder 3. Intheevent it is desired to utilize a cup-shaped packing 17 facing into the chamber 9 to inso sure that no air leaks past the cup packing 6 from said chamber, the outer periphery of the nut13 will be cut away a sufiicient distance to permit the interposition of the cup-shaped packing 17 between said nut and the wall of cylinder 3. Packing 6, or packings 6 and 17, as the case may be, are held in place on nut 13 by means of an annular washer 18 and a tubularretainer 19 which is held in place by cylindrical nut 14. The free edge of '90 each of the cup-shaped packings 6 and 7 is ressed against the inner wall ofcylinder 3 by means of cone expanders 20, and helical springs 21. Cup-shaped packing 7 is held in place on annular flange 22 of annular nut 14 by means of an'annular washer 23 and nut or follower 24 which, in turn, is held in place by nut 25 and lock nut 26 at the top of piston rod 10. The nut or follower 24 is formed with a relatively long I cylindrical bearing surface 27.

Piston rod 10 from a point-midway between'the cup pickings 6 and 7 is drilled to the top thereof to form an air chamber 28 and a screw threaded cap 29 is provided at the top and hermetically closing off the chamber 28 at this point. Oil ducts 30,30, extend from the bottom of the chamber 28 and open into the s ace between the said cup packings 6 and The retainer 19 is provided with a number of oil holes 31, 31,

near its upper edge and the space between the cup packings 6 and 7 serves as an oil nularvbufler 34 formed of some suitable soft material loosely surrounds piston rod 10 and rests on the bottom of chamber 9. This bufier or washer 34 may be a soft felt wick washer saturated with oil and serves to insure lubrication of the piston rod at this point and to absorb any oil that may leak down from the top and hold'it for the lubrication of the rod '10 in the bearing 33.

Normally, the cushion chamber 8 will be filled with oil to approximately the level shown in the drawings, the oil filling the spaces between the cup packings 6 and 7.

The act of filling the chamber 8 with oil preparatory to putting the device intoservice traps and confines a quantity of air or other elastic fluid in the chamber 28 and I make use of this chambered air or other elastic fluid in the operation of the device to aid and assist in maintaining a liquid seal between the lower extremity of the piston and the rebound chamber 9 and to keep the oil circulating to the bearing surfaces through the space above the cup washer 6.

It will be understood that the device will be initially charged with the required amount of air under pressure through a check valve conventionally shown at and the air pumped will flow into the cushion chamber 8 of the device and be confined there, as is now well understood in the art. In the operation of the device, with the embodiment of the invention as shown in the drawing, if no oil is forced past the cup washer 7, there will be no change in the level of the oil in chamber 28 and consequently no increase in the degree of compression of the air therein. On the other and, should oil leak past, or be forced past, the cup washer 7, it will raise the level of the liquid in the chamber 28 and increase the degree of compression of the air therein, and successive leakages of this character will build up a pressure in the chamber 28 and consequently place all the oil above the cup washer 6 under increased pressure until the pressure exerted by the air confined in chamber 28 equals or exceeds a minimum pressure in the cushion chamber 8, at which time the excess liquid will be transferred to a point above the cup washer 7. For example, with a pressure in the chamber 8 of, say, to 90 pounds per square inch for normal standing load, the pressure under working conditions varies therein from 150 to 200 pounds per square inch on the upstroke of the piston to 30 to 35 pounds per square inch on the down stroke thereof. From the foregoing, it will be seen that I make use of the pumping action of the air springv to force the oil escaping from the air chamber 8into another chamber and gradually build up a pressure therein which will exceed a minimum pressure of said chamber 8 and also avail myself to the pumping action of the chamber 8 at the minimum operating pressures below that built up in the auxiliary chamber 28 to positively draw the excess of oil from the said chamber 28 back into the chamber 8, at appropriate times during the operation of the device.

Should the cup washer 7, for any reason, break down while the spring is in use, the air chamber 28 will then take the rapid variations of pressures more or less direct and serve to protect the cup washer 6 from the. deleterious efl'ects of such rapid pressure variations and the consequent pumping action exerted on the chamber 28 by the pressure variations in chamber 8 will continue to serve to circulate the oil above cup washer 6, as the unimpaired portion of the cup washer 7 will continue to act as a seal between the chamber 8 and the space above the cup washer 6, to all bearing parts of the piston, and the device will continue to work efficiently.

The construction above described for returning the escaped oil to the cushion chamber 8 has marked advantages in view of the fact that it has no moving parts to get out of order and, further, the transfer of the oil is automatically accomplished only at those times when oil has accumulated.

Furthermore, it will be apparent that the oil between the long bearing 27 and the wall 3 in cushion chamber 8 is under pressure at all times, and I have discovered that by the employement of this arrangement, the device operates more smoothly and is more steady than similar devices in which such a bearing is absent.

I claim as my invention:

1. The method of operating an elastic fluid spring having a piston and sealin liquid on opposite sides of said piston whic 'method comprises subjecting one of the surfaces of the sealing liquid to the pressure of trapped elastic fluid, and subjecting the other surface of the sealing liquid to the pressure of trapped elastic fluid to force said liquid back to t e opposite side of said piston.

2. The method of operating an elastic fluid spring having a piston and sealing liquid on opposite sides of said piston which method comprises subjecting one of the surfaces of the sealing liquid to the pressure of trapped elastic fluid, subjecting the other surface of the sealing liquid to the pressure of trapped elastic fluid, and varying the relative pressures of said trapped elastic fluids to force said liquid back to the opposite side of said piston.

3. The method of returning sealing liquid to the high pressure side of the moving wall of an elastic fluid spring from the opposite side thereof, which method comprises causing the liquid which leaks past said moving wall from the high pressure side thereof to compress a constant mass of elastic fluid.

4. The method of returning sealing liquid to the high pressure side of the moving wall of an elastic fluid spring from the opposite side thereof, which method comprises collecting the liquid on the low ressure side of said moving wall, and causlng the collected liquid to compress a fixed mass of elastic fluid.

5. The method of operating elastic cushion devices comprising a cylinder closed at one end, a piston closing off a cushion chamber cushion chamber during the reciprocation of the piston, causing the collected fluid to build up a pressure in the trapped fluid compartment equal to or in excess of an operating pressure of the cushion chamber and availing of the pumping action of the members to force escaped fluid back into the cushion chamber.

6. The method of maintaining an oil seal in an elastic cushiondevice having a cushion chamber and an oil seal WhlCll COIlSlStS in feeding oil to a compartment having a trapped elastic fluid, causing the oil fed into said compartment to build up a pressure in said trapped compartment and availing of the pumping action of said members to force oil from the trapped fluid compartment into the cushion chamber. a

In testimony whereof I hereto aflix my signature.

JOHN J. MoELR OY. 

